The present invention relates to an electrophotosensitive material. More particularly the invention relates to the electrophotosensitive materials ideally utilized for the picture imaging apparatus such as copying machine.
Recently, an organic photosensitive materials are utilized for the electrophotosensitive material because the organic layer have wide freedom for the functional designing as well as workability and advantageous in production costs. It is well known that the high sensitive functional types electrophotosensitive material provides a photosensitive layer wherein the electric charge generating with exposuring to light function with a charge-generating ingredient and the electric charge-transferring function with a charge-transferring ingredient which ingredients are separated functions type photosensitive material as the organic photosensitive material.
There are variety of photosensitive layers which materials are functional parted electrophotosensitive material wherein comprising charge-generating layer at least contained with a charge-generating ingredient and charge-transferring layer at least contained with a charge-transferring ingredient and a binding resin, and photosensitive single type layer wherein both of a charge-generating ingredient and a charge-transferring ingredient are dispersed into a solvent thereof.
The photosensitive material wherein providing photosensitive multilayer have an advantageous in providing a high sensitivity and wide availability for selecting photosensitive material, because the functions thereof are separated into two, the charge-generating layer and the charge-transferring layer. layer.
Generally the negative electrificated photosensitive multilayer is structured as the conductive substrate is coated with charge-generating ingredient, and charge-transferring layer is further coated thereonto, because major charge-transferring layer is positive hole transfer type and giving durability to the surface is also required. However, those photosensitive multilayers for negative electrification may generate ozone into the ambient atmosphere, causing the sensitive layer, on negative electrified, to deteriorate and autotyping environment to contaminate, and the positive charged toner which is difficult to make, is necessary in developing prosess.
On the other side, it is recognized that the single layer type photosensitive material is not only charge positive but able to use negative charge toner to develop electrostatic latent image in the photosensitive layer, it is advantageous in widely selecting toner for the preparation, however, both of electron and positive hole are moved in one layer wherein either electron or positive hole are trapped, causing the residual potential to increase. Moreover, it is yet a question that electrophotographic characteristics such as the electrification characteristics, the sensitivity and the residual potential depend much up on the combination of charge-generating ingredient and charge-transferring ingredient.
In consideration of the problem abovementioned, the experiments to increase sensitivity of a single layer type photosensitive material are proposed in; An electrophotosensitive material comprising perylene pigment such as N,N'-dimethylperylene-3,4,9,10-tetracarboxydiimido and N,N'-di(3,5-dimethylphenyl)-perylene-3,4,9,10-tetracarboxydiimido as charge-generating ingredient, binding resin and acetonaphthylene as sensitizer, JP, A. No. 76840/1983, and an electrophotosensitive material comprising the perylene type pigment, polyvinylcarba sole resin as charge-transferring ingredient and terphenyl as sensitizer, JP,A. No. 119356/1984.
However, the these electrophotosensitive material are not yet complete to obtain the sufficient sensitivity. Especially, because of the perylene compound wherein having no spectrosensitivity to the long wave-length side, the charge-generating layer containing such a perylene compound yet result in obtaining insufficient sensitivity if it is combined with a halogen lamp of large spectro-energy for red.